This article is cited in 8 papers

70th ANNIVERSARY OF THE BIRTH OF V.A. RUBAKOV. REVIEWS OF TOPICAL PROBLEMS

Nonsingular cosmological scenarios in scalar-tensor theories and their stability

V. E. Volkova^ab, S. A. Mironov<sup>acd

a</sup> Institute for Nuclear Research, Russian Academy of Sciences, Moscow
^b Lomonosov Moscow State University, Faculty of Physics
^c Institute for Theoretical and Mathematical Physics of Lomonosov Moscow State University
^d National Research Centre Kurchatov Institute, Moscow

Abstract: This article gives a concise overview of the development and current status of studies on models of the early Universe without an initial singularity, namely the cosmological bounce and genesis scenarios, constructed within a broad class of scalar-tensor theories, specifically Horndeski theories and their generalizations. The review focuses on topics related to linear stability at the perturbation level against the background of nonsingular cosmological solutions: (1) the no-go theorem, valid for nonsingular cosmologies within the Horndeski theory, (2) updates on possible approaches to evade the no-go theorem, (3) the role of disformal transformations relating the Horndeski subclasses in generalized theories like DHOST, (4) effects on stability caused by additional matter coupling and the potential emergence of superluminal perturbation modes in the multi-component setting.

Keywords: scalar-tensor theories, nonsingular cosmology, stability, superluminality, cosmological bounce, genesis.

PACS: 04.20.Dw, 04.50.Kd, 98.80.Bp

MSC: 83F05

Received: September 24, 2024
Revised: December 11, 2024
Accepted: December 24, 2024

DOI: 10.3367/UFNr.2024.12.039826

 English version: Physics–Uspekhi, 2025, 68:2, 163–176

Bibliographic databases:

• 
• 
•